Dental shoulder-cutting instrument



Patented Jan. 15, 1924.

JOHN A. LENTZ, OF PHOENIX, ARIZONA.

DENTAL SHOULDER-CUTTING INSTRUMENT.

Application led May 31,

To all 'who/m, it may concern:

Be it known that I,`Jo1-IN A. LENTZj a citizen of the United States` and a resident ot Phoenix, county of Maricopa, and State .otl Arizona, have invented a. new and useful Dentalk Sliol.1lder(`utting Instrument, of which the following is a speeitication.

The present invention relates to improvements in dental instruments and has particular reference to a tool ior cutting a shoulder around a tooth to be, crowned. The principal object of the invention is to provide means in connection with this tool tor shielding the gum and the neighboring teeth from the cutting tool, which in this case is a rotary burr and for limitingat the saine time the lateral as Well as the longitudinal cutting action of the tool. Further objects and advantages will appear as the specifica.- tion proc-eed.. v

The preferred form of my device is illustrated in the accompanying f drawing in which Figure 1 shows my device attached to a straight dental engine(hant`lpiece; Figure 2, the same device attached to a bent hand piece; Figure 3 an enlarged detail view of a sheath used in connection with the cutting burr; Figure 4 a section through the same along line -l-4 of Figure 3; Figure 5 a crossseetion through the same along line 5 5 of Figure 3; Figure 6 a detail view of an upper tooth as it usually appears before the cutting operation is commenced; Figure 7r a detail View of the tooth having been prepared for the operation-with my instrument shown in place; Figure 8 a detail view of the same tooth after the operation has been performed and IFigures 9 to 1t` side and end elevations of various forms oi cutting burrs. While only one principal form of sheath has heen shown in this drawingit should-be understood that various changes or modifications may be'niade within the scope of the claims hereto attached without departing from the spirit of the invention.

The dental engine hand-pieee (1) shown in Figure 1 is of the usual form comprising a housing v supported therein and driven byany suitable means not shown in the drawing. The shat't (3) drives the burr of which various forms are shown in Figures 9 to 16. The burr (4) shown in Figures 9 and 10 is an ordinary smooth fissure burr cutting on the end and on the side adapted to cut both laterally and longitudinally and leaving a smooth surface,

Aend burr adapted to (2) and a shaft rotatably 1922. Serial No, 564,790.A

Figure 11 shows a cross cut fissure burr (6) adapted to be used for very hard tooth structure, such as enamel. Figures 13 and 14 show a smooth sided burr (7') adapted to eut longitudinally and Figure 15 a smooth cut laterally only. A.\ny ot' these burrs may be used in connection with my device. The invention resides principally in thersheath (l1) shown in detail in Figures 3, 4 and 5. This sheath has a tapered base (12) adapted to slide over the end (13) of the housing (2 and vto'be secured there in any suitable manner. From this base extends a cylindrical portion (14) having a longitudinal section (16) cutaway so aste surround the burr substantiallyon three sides by allowing the same to protrude on one side which latter side will be referred to as the active side ot the burr; The. cylindrical portion (14) thus provides a. sheath i'or the burr protecting the im as well as neighborii'ig teeth. It will be noted i'rom Figure 7 that the eut in the sheath slants away from the tooth toward its .outer end so as to allow a larger portion of the burr to be exposed at the end of the burr than near the base.

As a mere protection for the gum and the surrmmding teeth and the neighboring teeth it is sufficient if the sheath is coextensive in length with the burr but I preferably allow the sheath to extend beyond the burr as shown at (1,7) and to come to a point (18) lying on or near the axial center line ot' the burr. The function ot' the extension is to prevent the burr from penetrating the tooth laterally beyond a desired depth. it. serving at the same time to cause the shoulder to substantially follow the outlines ot' the circumference of the tooth. A step or indent (19) is provided in the sheath substantially on a line. with the end of the burr which step is adapted to ride on the shoulder during thecutting .operation so as to limit the longitudinal cutting of the tooth beyond the. desired depth.

The sheath is provided in its back with a slot (21) or suitable iierlorations allowingr the debris to be cleared away.

The operation of the device will be readily understood particularly with the aid of the Figures 6 be 8 in the drawing. Figure 6 shows the tooth in its normal form bet'ore it is worked on. By the use of tools not described in this specification it is rei with any neighboring the step (19) in the sheath duced so as to present atapered end as shown indotted lines (20) in Figure 6. Now m tool is applied as shown in Figure 7 and therotating burr allowed to en a-ge the tooth while the sheath prevents the urr from coming in Contact with the gum or teeth.- The final shape of the shoulder` mayy be 'somewhat as shown in Figure 8, the point (18) of the sheath engaging thetooth above. the shoulder in the ease of an upper tooth and limiting thereby the lateral penetration of the burr. After the shoulder has been started will ride on the same and thereby limit the longitudinal netration of the burr. l

ItV will be understood from the foregoing description that the sheatlras such will be o 'erative and perform an important funeplaced over the flange burr and a sheath for tion without the point l(18) and the step (19) and I wish to be protected on this point by itself, as Well as on the other features.

The orm shown in Figure 2 varies from that shown in Figure 1 only in so far as it has been adapted to be used with a bent hand-piece. It will be seen that for this purpose I provide a bearing (22) inside the housing engaging the same threadedly and provided with an external flange (23) lying on the outside of the housing (24) or the shaft (26). The base (21) of mysheath is (23) and may be secured thereto in any suitable manner.

I claim:

1. A dental instrument for cutting a shoulder into a tooth comprising a rotary the same leaving one after the latterhas side ofthe burr free for lateral engagement with the tooth at any desired elevation.

2. A dental instrument for cutting a shoulder into a tooth comprising a rotary burr and a sheath for the same leaving one side of the burr ree for lateral engagement with the tooth at any desired elevation, the sheath extending beyond the burr tor laterally limiting the depth of the leut.

3. A dental shoulder into a tooth comprising a rotary burr and a sheath for the same leaving 'one side of the burr tree for lateral engagement with the tooth at any desired elevation, the sheath extending beyond the-burr for laterally limiting the depth of the out, and a step beingformed 1n the sheath on a level with the end' of the burr adapted to ride on the shoulder for limiting the out longitudinally. 4. A dental instrument for cutting a shoulder Vinto 'a tooth comprising a rotary -burr and a sheath for the same leaving one sideof the burr free for lateral engagement with the tooth -at any desired elevation, with the shield formed toridefion ythe shoulder been started for limiting the out longitudinally.v 4, 5; A dental instrument Jfor cutting a shoulder into a tooth comprising a rotary burr and a sheath for the same leaving one instrument' for cutting a side of the burr free for lateral engagement with the tooth at any desired elevation, wit an opening in the sheath allowing the dbris to pass therethrough. f

JOHN A.`LENTZ. 

